The present invention relates to a disc control method and a disc control unit for recording digital video data, audio data, and user data onto disc media including magneto-optic discs, phase-change discs, and magnetic disks.
Conventionally, a Digital Video Disc (DVD) unit has been used for playing back digital video data from a disc. A DVD, a 12 cm optical disc capable of storing 4.7 GB of compressed digital data, allows the user to play back at least two hours of video/audio data.
Also available for use in recording and playing back digital data to or from a disc is a DVD-RAM unit. The DVD-RAM unit, capable of storing 2.6 GB of digital data on a 12 cm phase-change disc, allows the user to record and play back digital data repeatedly.
FIG. 24 is a block diagram showing the configuration of a DVD-RAM unit. The unit records and plays back video/audio data as follows. Upon receiving video/audio data 2401, a video/audio coding circuit 2402 compresses and multiplexes the data. A recording signal processing circuit 2403 shuffles the data and adds error correcting codes to it. A head 2405 writes the coded video/audio data from the recording signal processing circuit 2403 onto a disc 2406 under control of a CPU control circuit 2404. To play back video/audio data, the head 2405 reads data from the disc 2406. The CPU control circuit 2404 controls the optical head, spindle motors, and so on. A played-back signal processing circuit 2407 checks the data for errors and corrects them, if necessary, and de-shuffles the data. A video/audio decoding circuit 2408 decodes the data and sends the decoded video/audio data to an output section 2409.
The DVD described above contains data called xe2x80x9cnavigation data.xe2x80x9d The navigation data is not video/audio data but disc management data provided to help the user fully utilize video/audio data on the disc. The navigation data, which appears once or more times on the disc, is composed of the following data:
{circle around (1)} Where is a program located on the disc? Correspondence between program numbers and program recording addresses is recorded. This data allows the user to know where each program is recorded on the disc.
{circle around (2)} Special playback data (fast forward, fast rewind, slow playback) An address to which control is to be passed next is recorded for each rotation speed.
{circle around (3)} At which address is playback data recorded when a multi-language option (Japanese, English) is selected?
{circle around (4)} At which address is playback data recorded when a multi-angle option (viewing direction; for a baseball game, in the center fielder direction or in the catcher direction) is selected?
{circle around (5)} At which address is playback data recorded when a multi-story option (a happy ending or tragedy) is selected?
{circle around (6)} Others
Read-only DVD""s navigation data is not changed once recorded, while writable DVD""s navigation data may be changed. In addition, unusable data exits. For example, because video/audio data is variable-length, navigation data such as {circle around (1)} and {circle around (2)} is rewritten. On the other hand, multi-option data such as {circle around (3)}, {circle around (4)}, and {circle around (5)}, cannot be recorded in real time while maintaining synchronization. That is, a problem with conventional navigation data is that it is designed for read-only. Basically, it is not re-written.
Although the DVD-RAM unit is described above as a video data recording unit, it is not designed for recording video data in practice. Therefore, the DVD-RAM unit has not video data recording navigation data.
In view of the foregoing, it is an object of this invention to provide a disc control method for recording and playing back first data, second data, and control data on a disc medium, the control data being generated by a CPU (Central Processing Unit) control circuit, wherein the control data contains:
a. a number of a first data group, a sector number of the first data group, an offset block number containing second data groups synchronizing with the first data group, and a sequence number of the starting second data group within the offset block;
b. the number of a destination first data group after which first data groups to be merged, the number of first data groups to be merged, and the number of the first data group from which first data groups are to be merged, for changing a sequence of first data groups during playback;
c. the number of a destination sector after which blocks are to be inserted, the number of blocks to be inserted, and the number of the sector from which blocks are to be inserted, for changing the sequence of blocks during recording; or
d. the number of the block containing a destination second data group after which second data groups are to be inserted, the sequence number of the destination second data group within the block, the number of second data groups to be inserted, and the number of the block from which second data groups are to be inserted, for changing the sequence of second data groups during recording,
the disc control method comprising the steps of:
a. when recording data,
(i) reading the control data from the disc when the control data is on the disc;
(ii) reading data;
(iii) recording the data on the disc by referencing the control data; and
(vi) recording the updated control data on the disc; and
b. when playing back data,
(i) reading the control data from the disc;
(ii) playing back data from the disc according to the control data; and
(iii) outputting the data.
For example, this method allows the user not only to play back video data and its synchronizing audio data but also to re-write them as well as their control data. Therefore, the user can re-write data and, in addition, perform a quick and precise search, special playback (fast-forward, fast rewind, slow playback), and editing easily even for data that was re-written.